1. Field of the Invention
The present invention relates generally to cables and associated terminators, and more particularly to terminators used for Small Computer System Interface (SCSI) buses.
2. Description of the Related Art
In the ever-expanding environment of high technology infrastructure, SCSI architecture remains the performance choice for high-end computer users seeking ways to optimize and maintain high-performance work stations, small business servers, and complex networks alike. Faster peripheral devices, data-intensive applications, and more robust internet connections all require the fastest available data transfer, increased capacity, and better reliability than has been provided with prior art products and systems. The demand has fostered consistent technological advances, and SCSI technology maintains consistent growth and development to meet the demand.
The typical computer work station or network server includes a plurality of peripheral devices connected to the system motherboard across a peripheral component interconnect (PCI) bus. In some applications, a SCSI host adapter connects to the PCI bus to enable the connection of a plurality of peripheral devices such as hard disk drives, optical media recording and play back devices, scanners, Zip(trademark) drives, and the like. Additionally, a SCSI motherboard may be used, enabling the connection of a plurality of peripheral devices, and with the same associated considerations as described above. The increase in speed of processors, the increase in processing speed and efficiency of operating systems, and the increase in clock speed and bandwidth of PCI buses all contribute to the requirement for increased data transfer rate of SCSI peripheral devices.
As is known, a SCSI bus requires termination at both ends of the bus. This termination, generally, provides necessary impedance matching. Without termination, the bus is susceptible to noise and signal corruption caused by electronic pulses reflected from non-terminated ends. In typical configurations, external devices are terminated by either attaching a terminator to the last device in a chain of devices, or by enabling a built-in terminator of the last device in a chain of devices. For internal devices, a terminator is typically attached to the end of a multi-device SCSI device cable.
As SCSI technology evolves to provide for faster and faster data transfer rates, the requirement for termination remains, and is even more critical at the increased clock rates currently being implemented. While external peripheral device configurations typically implement a terminator attached directly to the device, or configure the device with jumpers or DIP switches for termination, internal devices are typically attached to the SCSI host adapter, or SCSI controller, with a ribbon-type SCSI cable having a plurality of connectors that attach to the individual devices. The last connector on the cable is then usually attached to a terminator to terminate the end of the bus. Device cables are usually manufactured to accommodate a typical system configuration of three, five, or seven devices, although any number of devices up to the host adapter capacity is possible. After the internal devices are connected to the plurality of connectors on the device cable, the last connector on the device cable is used to connect to a terminator, also known as a terminator block, to terminate the bus.
FIG. 1A illustrates a typical connection diagram of internal SCSI peripheral devices. A SCSI host adapter 10 is shown that connects to a PCI bus (not shown) of a computer system. Exemplary SCSI peripheral devices 12 are shown that would be mounted in a device bay or location within the computer system. A SCSI device cable 14 connects the SCSI peripheral devices 12 to the SCSI host adapter 10. Connectors 16 attach the SCSI device cable 14 to each of the SCSI peripheral devices 12. A terminator 18 is shown at the terminal end of the SCSI device cable 14.
Following the last device 12 in a chain of devices 12, a last connector 16 is typically used to connect the SCSI device cable 14 to a terminator block, resulting in a terminator 18 as shown in FIG. 1A. FIG. 1B shows a detailed view of the terminator 18 shown in FIG. 1A. In FIG. 1B, SCSI device cable 14 is shown leading to the terminator 18, but connector 16 is not shown. Connector 16 (not shown) is used to connect the SCSI device cable 14 to a terminator block 20 in the same manner as connectors 16 attach SCSI device cable 14 to SCSI peripheral devices 12, typically using pins and holes or other similar quick connect methods. Connection cover 22 is typically fitted over the connector (not shown) to cover the point of connection preventing inadvertent contact with any points of connection, accumulation of dust or other debris, and generally protecting the SCSI device cable 14, the connector (not shown), and the terminator block 20. The resulting unit including the SCSI device cable 14, the terminator block 20, and the connection cover 22, is collectively referred to as the terminator 18.
This prior art terminator 18 used for terminating one or more internal SCSI peripheral devices 12, effectively terminates the end of the SCSI bus, but is deficient for a number of reasons, some of which are herein discussed. As technological advances in SCSI design have provided for increasing numbers of SCSI peripheral devices 12 to be connected to a single SCSI host adapter 10 (see FIG. 1A), space and airflow have become increasingly important considerations for computer system configuration. FIG. 1C shows an exemplary internal SCSI peripheral device 12 configuration. A typical drive bay 24 is shown with six representative SCSI peripheral devices 12. The SCSI peripheral devices 12 could be hard disk drives, CD-R drives, other optical media drives, Zip(trademark) drives, and the like. A typical SCSI host adapter 10 (see FIG. 1A) accommodates more than six internal SCSI peripheral devices 12, and therefore FIG. 1C illustrates space and airflow requirements for less than the maximum number of devices that might be connected to a single host adapter 10. SCSI peripheral devices 12 are typically installed in drive bay 24 as shown, and connected to a SCSI host adapter 10 (see FIG. 1A) with SCSI device cable 14. In addition to SCSI device cable 14, power is supplied to each SCSI peripheral device 12 at power connection 26. FIG. 1C does not show power cabling, but it should be appreciated the additional cabling presents further space management difficulty, and further restricts airflow through and around SCSI peripheral devices 12.
Terminator block 20 is shown connected to a last connector 16 of SCSI device cable 14. Terminator block 20 is shown without connection cover 22 (see FIG. 1B). A common problem with prior art terminators 18 (FIGS. 1A and 1B) is that connection cover 22 (FIG. 1B) often becomes detached from terminator block 20. The detached connection cover 22 presents a potential source of foreign object damage if it should fall into the computer system against other devices, connections, wires, and the like. Additionally, a detached connection cover 22 can also restrict airflow in already compact spaces which can damage individual devices or degrade system performance due to accumulated heat. Further, the exposed connections at connector 16 attached to the terminator block 20 present a potential source of electrical short or equipment damage if the area of connection is forced against a metal case, a metal exterior of another device, or alongside cabling or wire connections.
It should be further appreciated from FIGS. 1A, 1B, and 1C that terminator 18 has a length, a width, and a depth. Although the terminator 18 is connected to essentially the end of a SCSI device cable 14, it requires space near the last SCSI peripheral device 12 in the plurality of SCSI devices that are connected to the SCSI host adapter 10 (See FIG. 1A) with SCSI device cable 14. As mentioned above, this can result in the terminator 18 being forced in between devices, along side system cards, devices, cabling, and the like, all presenting a potential source of equipment damage, and even operator injury in the case of an electrical short. The size of the terminator 18 further restricts necessary airflow within the already compact and densely filled space of a computer system case or cabinet.
Forcing a terminator 18 into a compact and densely filled space of a computer system case or cabinet can put stress on the individual wire connections at connector 16. Unlike the connectors 16 connected to SCSI peripheral devices 12 which are fixed in place within drive bay 24, the terminator 18 (FIGS. 1A and 1B) is moved into any number of positions and orientations in order to get it to fit within drive bay 24 and system. The positioning and orientation of terminator 18 can put varying stresses on the individual wire connections of connector 16 attached to terminator block 20 resulting in a potential source of incomplete or broken connections, inoperable equipment, and electrical shock.
What is needed is a terminator for a SCSI bus that can be used with internal SCSI devices that effectively terminates the SCSI bus while presenting a minimum size and space requirement, provides sturdy and durable connections for the wires of a SCSI device cable, and is light and aerodynamically designed to minimize airflow restriction. The terminator should not present a risk of foreign object damage within a computer system case or cabinet, and should be compatible with existing and developing SCSI technology.
Broadly speaking, the present invention fills these needs by providing an inventive overmold cable terminator and method for making the same. The present invention can be implemented in numerous ways, including as an apparatus, a process, a device, or a method. Several embodiments of the present invention are described below.
In one embodiment, a cable terminator is disclosed. The cable terminator includes a printed circuit board which has termination circuitry. The cable terminator further includes a ribbon cable with a first end and a second end. The first end of the ribbon cable is electrically connected to the printed circuit board to enable termination at the first end of the ribbon cable. An encapsulating mold encloses the printed circuit board and first end of the ribbon cable.
In another embodiment, a SCSI cable with an integrated terminator is disclosed. The SCSI cable with an integrated terminator includes a ribbon cable with a first end, a second end, and at least one device connector between the first end and the second end. The SCSI cable with an integrated terminator further includes a printed circuit board with termination circuitry. The termination circuitry is electrically coupled to the first end of the SCSI cable. An overmold is included which seals the printed circuit board and the first end of the SCSI cable. The overmold retains a single output path for the SCSI cable that extends to the second end.
In still a further embodiment, a method for making a ribbon cable with an integrated terminator is disclosed. The method includes providing a terminating circuit board and connecting an end of a ribbon cable to the terminating circuit board. The terminating circuit board with the end of the ribbon cable is inserted into a mold. The method further includes injecting an encapsulating material into the mold.
The advantages of the present invention are numerous. One notable benefit and advantage of the invention is the size. Smaller and much thinner than prior art, the present invention maintains a maximum achievable airflow in and around the plurality of components within the computer system case or cabinet. The slim profile of the present invention is aerodynamic to minimize airflow restriction within the system in which the present invention is implemented, and further, does not impede access to adjacent cards, components, connections, and the like.
Another benefit is the single-component construction of the present invention. Unlike prior art, the present invention has no detachable parts that can become dislodged to present a potential for foreign object damage to adjacent devices, components, and wiring of a computer system.
An additional benefit is the ease of manufacture of the present invention. A method of the present invention utilizes known processes implemented in other aspects of device and system production, and presents a simple, compatible method of manufacture for ease of implementation in prior and developing art.
Yet another benefit is the robust functionality of the present invention. The inventive terminator utilizes fixed connections that are then protected from stresses or exposure to potential sources of damage, electrical short, and the like.
Other advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.